Currently, in the field of the production of propellant devices, notably for munitions, explosive materials having burn rates ranging from a few millimeters to a few tens of millimeters per second are used. Given that the objective of a propellant device is to deliver a maximum impulse in a bore of a given caliber, it is conventional to seek to increase the explosive burn area of the propellant device. As a consequence, the mass flow rate of burnt explosive material, which corresponds directly to the impulse created by the propellant device, is proportionately increased. Specifically, the mass flow rate Dm of a material having a burn velocity Vc, a density ρ and a burn area S satisfies the following equation: Dm=Vc×ρ×S. This mass flow rate Dm is directly proportional to the force generating the vector displacement. The impulse is then the integral of this force over the time during which it is exerted.
To increase the explosive burn area of the propellant device, it is general practice to have a central channel along the core of the explosive charge of the propellant device. This central channel enables the explosive burn area to be substantially increased.
However, this standard technique has two major drawbacks. Firstly, the central channel provided along the core of the explosive charge of the propellant device weakens the latter when exposed to accidental external attack. This sensitivity of propellant devices, and therefore potentially of the munitions of which they form part, is well known, particularly as regards attacks such as “heavy/light fragments”. Such attacks and the associated reactions are modeled and grouped under the name “channel effect”.
In general, as regards munitions, most countries evaluate and classify their reactions with respect to standard types of attack and establish standards for the purpose of possessing only low-risk munitions. One of the major objectives when developing new munitions is therefore in particular to minimize the risk of a violent reaction of these munitions to accidental external attack. The channel effect tends to increase the violence of munition reactions with respect to such attacks, which constitutes a serious problem.
The second major drawback associated with the current technique lies in the reduction in specific energy efficiency per unit volume. This is because, quite obviously, the provision of a central channel in a propellant device, although it clearly does increase the impulse thereof, it also increases the volume by increasing the height for a given mass of propellant.
The aim of the invention is in particular to alleviate the afore-mentioned major drawbacks. The invention therefore makes it possible to increase, for a constant volume, the impulse of a propellant device while reducing the risk of violent reaction to external accidental attack by eliminating the channel effect of the current propellant devices.